Thread Tools
Jun 01, 2001, 04:50 AM
Mie oo Karjala poikii
Tyson's Avatar

Speed 280BB - direct drive or not?


My Pfalz somehow managed to hit a rock and now I've got a Simprop Speed 280BB with a broken 5:1 gearbox. According to my knowledge, Speed 280BB needs a gearbox to be effective and is not very good as direct drive.

I would like to know if someone has got experiences (good or bad) from direct drive Speed 280BB? Which prop/batterypack to use, etc.? Or should I forget the idea and buy new gearbox instead?

Thanks in advance!

-=Mike=-

Sign up now
to remove ads between posts
Jun 01, 2001, 06:06 AM
Registered User
Andy W's Avatar
I'm "using" one in a DMA flea, direct, with the Graupner 4.7x2.25 folder. No flights, or even a final choice on cell count, yet.. Thinking 7 cells..
..a
Jun 01, 2001, 07:31 AM
Registered User
Tyson:
I am flying my Flea with the 280BB using 7/600ae's,Grapuner 4.7x 4.7. Don't have all the tech. stuff to ck. amps. etc. But can say
it flys for about 6min. with some throttle mgmt. and is not too hot after flight, I don't think you could pull a big slow fly prop without the gear box. Appels & Oranges!
Andy are you EVER going to finish that Flea?
Jun 01, 2001, 07:59 AM
H301 Libelle Pilot
Dr. Jet's Avatar
Andy,
Are you ever going to finish and fly those Fleas?
Jun 01, 2001, 08:26 AM
Balsa Flies Better!
Tyson

I've used Speed 280BBs without gearboxes, but they're kind of marginal. The problem is that a Speed 400 weighs only an ounce more by the time that you come up with a 7 cell 600 AE pack. The motor actually does fine on 8 cells too, but doesn't match the power output of a Speed 400.

I've also tried Speed 280BBs on either an 8 cell 720 NiMH pack and 7 cell 350s. In both cases, the airplane flew, but it was always a little lacking in zip. I think the right batteries are the Panasonic 650 mAH NiMH cells (8 maybe 9 cells?) which handle more current than the 720 NiMH cells.

Realistically though, on the same batteries and propped appropriately, an Astro 010 is a better choice direct drive. On the other hand, I've got 3 of the Speed 280BBs geared (MTM wasps) and they work very well. I'm scratching my head as to why gear the Astro motor when this combo is available.

Sam Brauer
Norwalk, CT
Jun 01, 2001, 10:55 AM
ὅπερ ἔδει δεῖξαι
Gerald's Avatar
A plane like the Flea is about the only thing out there that the 280BB will work well in as direct drive. The Flea is sort of a mini pylon racer and since it has such low drag and goes fast the 280BB can use a small prop that will let it spin at high RPM.

The 280BB is only efficient at higher RPMs so it really needs gearing to be effective. I have a mini X250 (70% scaledown) that I use a 280BB in with 4:1 Horst gearbox and 8x720mah NiMH cells. Even this plane is pretty fast and turns a 7x7 speed prop.

In another plane, a Guillows SE5A Biplane which is a conversion from the rubber powered kit, I run a 280BB on a 4.4:1 box but with a 9x6 slowflyer prop. In this case its only on 7 of the NiMH cells.

In my 1/16 scale P-38 Lightning I'll be running twin 280BBs with 5:1 gearing to turn 3 bladed 9x7 props.

Don't even try to fly your Pfalz with the motor direct drive. At best it won't fly, at worst you'll put too much prop on it and burn up the motor. Just get a new gearbox, you'll be needing it for most anything else you want to use the motor in if not the Pfalz.
Jun 02, 2001, 04:01 AM
Mie oo Karjala poikii
Tyson's Avatar
Quote:
Originally posted by Gerald:
...
Don't even try to fly your Pfalz with the motor direct drive. At best it won't fly, at worst you'll put too much prop on it and burn up the motor. Just get a new gearbox, you'll be needing it for most anything else you want to use the motor in if not the Pfalz. [/B]
I was thinking about using it in my scratch built 'pylon racer'-style plane (I did not even think to use it in Pfalz).

Maybe I should just try it. It's the only way to find out whether it's suitable or not. Do you think 5x3 prop would be too large?

-=Mike=-

Jun 02, 2001, 03:28 PM
ὅπερ ἔδει δεῖξαι
Gerald's Avatar
A 5x3 will work but I don't know of any that size except the Cox prop. The Graupner 4.7x2.4 Cam folder that Andy W. mentioned works well, I've seen the flea fly with this prop. 7 600AE nicad cells is about the limit for direct drive with that prop. You should keep the max current below 8 amps. For all-out top speed the Cam 4.7x4.7 speed prop will draw about 8.6 amps static on 6 of the nicads.

[This message has been edited by Gerald (edited 06-02-2001).]
Jun 04, 2001, 05:59 AM
Registered User
Bill Glover's Avatar
I just posted on this subject in the slow flyers area. I'm currently using a 280BB direct drive with the CAM 4.7x2.3 folder and 6x500AR. Static current draw is about 9.4A, I get 6 min aerobatic flights (using throttle) in an o/d 28" span model, AUW approx. 12 oz. Have also used 7x720 nimh, current draw was a lot lower (about 7.4A), flight time about 8 mins.
Jun 04, 2001, 06:12 AM
Mie oo Karjala poikii
Tyson's Avatar
Thanks a lot guys!

I'll try with the CAM 4.7x2.3 folder and 6x500AR and 7x600AE packs.

-=Mike=-